A hard disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read/write head that is positioned over a specific location of a disk by an actuator.
A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. Write heads make use of the electricity flowing through a coil, which produces a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
Increasing areal density (a measure of the quantity of information bits that can be stored on a given area of disk surface) is one of the ever-present holy grails of hard disk drive design evolution. In turn, as recording tracks in HDDs become narrower and narrower, there is a need for more accurate and sustainable head positioning. The natural frequency of components that make up an HDD is determined by the materials used and the shapes thereof. If the natural frequency of the components is the same or similar, there are problems in terms of increased vibration due to resonance. This resonance-induced vibration affects read/write operations and, therefore, the resonance of each component is often designed so as not to be the same or similar.